Electronically servo-assisted bicycle gearshift and related method

ABSTRACT

A method for electronically servo-assisting a bicycle gearshift to allow compensation for misalignments between the chain of a bicycle gearshift and one or more sprockets of the gearshift, the method including the steps of: driving an actuator of a bicycle gearshift to displace a chain of the gearshift in an axial direction with respect to a gearshift group comprising at least two sprockets; receiving information on the desired alignment between the chain and a predetermined sprocket of the gearshift group; and setting an adjustment variable, of a logic value associated with the gear ratio relative to the predetermined sprocket, to a value corresponding to the displacement carried out in the step of driving the actuator.

FIELD OF THE INVENTION

The present invention concerns an electronically servo-assisted bicyclegearshift and a method for servo-assisting a bicycle gearshift, as wellas a program and an electronic circuit for carrying out the method.

BACKGROUND

Electronically servo-assisted bicycle gearshifts are described in U.S.Pat. Nos. 5,480,356; 5,470,277; and 5,865,454; 6,047,230; Europeanpatent application EP 1 103 456; and in German patent application DE 3938 454 A1.

In particular, EP 1 103 456 describes a type of gearshift wherein theposition transducers are of the absolute type, capable of providing anelectrical signal indicating the absolute position of the derailleurs,this type of transducer takes into account the actual position of thederailleurs, therefore operation of the device is not detrimentallyaffected by displacements of the gearshift mechanism which occur whenthe device is switched off.

For correct operation of the gearshift in normal ride operating mode(i.e. wherein the gearshift is commanded manually by the rider orautomatically or semi-automatically by the electronic control unit), therear and front actuators must preliminarily be aligned in a startposition, used as a reference (together with information on the positionof the various sprockets and/or on the distance or pitch betweenadjacent sprockets) to displace the chain between adjacent sprockets tocarry out the gear-shiftings. The start or reference position is usuallythe one in which the chain is at the sprocket with the smallestdiameter.

In the prior art mechanically commanded gearshifts, the alignment in thestart position is carried out with manual adjustment devices whichprovide for correcting the position of a steel cable which is used toactuate the displacements during a gear-shifting.

In electronically servo-assisted gearshifts, the electronic controlunit, to carry out the displacement of the chain between two adjacentsprockets, drives the actuator referring to logic positions (logicvalues) representative of the physical positions of the varioussprockets.

In these types of gearshifts, the setting of the start or referenceposition is usually carried out in the factory, causing the derailleur,in absence of a control signal of the actuator, to be at the sprocketwith the smallest diameter.

In the event of replacement of the rear wheel, it may occur that the newrear wheel is of a slightly different size from the replaced rear wheel,in particular as far as the hub and the sprockets or pinions of the reargearshift group are concerned.

Due to the displacement or the slightly different size, the chain andthe sprocket may not be perfectly aligned, with consequences beingproduction of noise and increased risk of incorrect operation of thegearshift itself. The front gearshift group is also subject tomisalignments. The invention described herein seeks to overcome theseand other shortcomings in the prior art.

SUMMARY

The object of the present invention is to make it possible to overcomemisalignments in a sufficiently rapid manner as to be able to do soduring a cycle race, in particular whilst in motion, without the need tomount the bicycle on a stand.

In a first aspect thereof, the present invention concerns a method forelectronically servo-assisting a bicycle gearshift, including the stepsof:

a) driving an actuator of a bicycle gearshift to displace a chain of thegearshift in an axial direction with respect to a gearshift groupcomprising at least two sprockets, in a first direction or in a seconddirection opposite to the first direction,

b) receiving information on the desired alignment between the chain anda predetermined sprocket of the gearshift group, and

c) setting an adjustment variable of a logic value associated with thegear ratio relative to the predetermined sprocket to a valuecorresponding to the displacement carried out in step a) of driving theactuator.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention shallbecome evident from the following detailed description of presentlypreferred embodiments thereof, which is with reference to the attacheddrawings. In the drawings:

FIG. 1 schematically illustrates a perspective view of a bicycleequipped with an electronically servo-assisted gearshift according tothe present invention,

FIG. 2 illustrates a block diagram of the electronically servo-assistedgearshift according to the preferred embodiment of the presentinvention,

FIGS. 3 to 5 schematically illustrate different embodiments of storagemeans of the gearshift according to the present invention,

FIG. 6 illustrates a flow chart exemplifying a mode selection of thegearshift according to the invention,

FIGS. 7 and 8 jointly illustrate a flow chart of the preferredembodiment of a setting operating mode of the gearshift according to thepresent invention, and

FIG. 9 illustrates a flow chart of an embodiment of an adjustmentoperating mode of the gearshift according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, a bicycle 1, in particular a racing bicycle,includes a frame 2 formed in a known way to define a support structure 3for a rear wheel 4 and a fork 5 for a front wheel 6. A handlebar 70 isoperatively connected to the fork 5.

The frame 2, at its lower portion, supports an axle of the pedals orpedal unit 7, of a conventional type, to actuate the rear wheel 4through an electronically servo-assisted gearshift system according tothe invention, generally indicated with reference numeral 8.

The gearshift system 8 includes a rear gearshift group 9 and a frontgearshift group 10. The rear gearshift group 9 includes a plurality ofsprockets 11 having different diameters and being coaxial (axis A) withthe rear wheel 4. The front gearshift group 10 includes a plurality ofsprockets or crowns or gears 12 having different diameters and beingcoaxial (axis B) with the axle of the pedal cranks 7.

The sprockets 11 of the rear gearshift group 9 and the sprockets 12 ofthe front gearshift group 10 are selectively engageable by a loopedtransmission chain 13, to provide different gear ratios, through theelectronically servo-assisted gearshift system 8.

The different gear ratios are obtained by moving a rear derailleur 14 ofthe rear gearshift group 9 and/or a front derailleur 15 of the frontgearshift group 10.

Making reference to FIGS. 1 and 2, the rear derailleur 14 and the frontderailleur 15 are controlled by a respective actuator 16, 17 whichtypically includes an articulated parallelogram mechanism and anelectric motor with reducer to deform the articulated parallelogram.

Rear and front transducers 18, 19 respectively sense the location of therespective derailleur and respectively cooperate with the respectiveactuator 16, 17 to position the associated derailleur 14, 15.

The details of the construction of the derailleurs 14, 15, of therespective actuators 16, 17 and of the respective position sensors ortransducers 18, 19 are not illustrated here since the present inventionis not concerned with their specific construction. For further detailsthereof refer, for example, to the description in the aforementionedpatent applications and patents which are incorporated herein byreference.

In particular, the transducers 18, 19 are preferably of the typedescribed in EP 1 103 456 A2, suitable for providing electrical signalsindicating the absolute positions of the derailleurs 14, 15.

An electronic power board 30, equipped with a battery, provides theelectrical power to motors of the actuators 16, 17, to the transducers18, 19, to a microprocessor electronic control unit 40 and preferably toa display unit 60. The battery is preferably of the rechargeable typeand the rear derailleur 14 can include, a dynamo-electric unit of a typeknown in the art for recharging the battery.

The electronic control unit 40 is preferably a logic unit of a typeknown to those skilled in the art. The control unit 40 is preferably asingle unit housed in the display unit 60. Alternatively, the controlunit 40 may be housed in the electronic power board 30 or in a commandunit. Further, the control unit 40 may include multiple units housed inone or more of the display unit 60, power board 30, or a command unit.

The electronic power board 30 is preferably housed in one of the tubesof the handlebar 70, in one of the tubes of the frame 2, for example ata support for a drinking bottle (not illustrated), or in the displayunit 60, which is preferably housed centrally on the handlebar 70.

The information transfer between the various components is carried outthrough electrical cables, preferably housed inside the tubes of theframe 2, or alternatively using wireless devices known in the art, forexample utilizing the Bluetooth protocol.

The rear and front derailleurs 14, 15 are controlled by the actuators16, 17 which are controlled by the electronic control unit 40.Preferably, the control unit 40 receives upwards or downwardsgear-shifting request signals from manual command devices.Alternatively, the control unit may generate request signalssemi-automatically or automatically for the rear gear shift group 9. Themanual command devices preferably include levers 43, 44 associated withthe brake lever 41, for respectively producing upwards and downwardsgear-shifting signals. The manual command devices also preferablyinclude levers 45, 46 associated with the brake lever on the handlebar70, for producing upwards and downwards gear-shifting signals for thefront gearshift group 10 (the levers 45, 46 are not illustrated in FIG.1 for the sake of clarity).

As an alternative to the levers 43, 44 (45, 46) two manually operatedbuttons, or two buttons which can be operated by a swing lever can beprovided.

The electronic control unit 40 is also coupled with two transducers 18,19 which produce signals indicative of positions of the front and rearderailleurs 15, 14 and to stop the motors of the actuators 16, 17 whenthe desired gear ratio has been reached. For example, when thederailleur 14 or 15 has reached one of sprockets 11 or 12 from anadjacent sprocket, a signal is transmitted by the transducer to theelectronic control unit which notifies the unit 40 to turn off power tothe actuator.

In an alternative embodiment, the motors of the actuators 16, 17 arestepper motors driven by a selected number of steps by the control unit40 for each upwards or downwards gear-shift. In this embodiment thetransducers 18, 19 are used to provide a feedback signal to theelectronic control unit 40 to re-actuate the motors of the actuators 16,17 in the case in which the physical position corresponding to theadjacent sprocket 11 or 12 has not been reached. This may occur, forexample, if the resisting torque offered by the derailleur 14, 15, whichis to some degree dependent upon how the rider is pedalling, is toohigh, that is greater than the maximum torque which can be delivered bythe stepper motor.

More specifically, according to the present invention, the electroniccontrol unit 40 includes a rear counter 47 and a front counter 48. Thecounters 47, 48 can, for example, each receive data from a register or avariable stored in a memory cell.

The electronic control unit 40, in the normal ride operating mode of thegearshift system 8, drives the actuators 16, 17 and tracks theirposition increasing or decreasing the counters 47, 48, for example byone unit for every step of the stepper motor and/or based upon thereading of the transducers 18, 19.

The electronic control unit 40 also includes rear storage means 49 andfront storage means 50, based upon which the electronic control unit 40determines (in the ways described later on with reference to FIGS. 3-5)the logic values which the counters 47, 48 have when the derailleurs 14,15 are positioned as desired with respect to sprockets 11, 12.

In other words, if the chain 13 is at a first sprocket 11 (12) and thecounter 47 (48) has a first logic value, when the rider actuates themanual upwards gear-shifting request command 43 (45) (or when such arequest is generated by the electronic control unit 40 itself), theelectronic control unit 40 provides for driving the actuator 16 (17) todisplace the chain along axis A (B) in a first direction until thecounter 47 (48) reaches the logic value (read directly from the storagemeans 49 (50) or derived from the information read from the storagemeans 49 (50)) associated with the adjacent sprocket 11 (12), withimmediately larger diameter. The chain 13 is then at the adjacentsprocket 11 (12), with immediately larger diameter. When the rideractuates the manual downwards gear-shifting request command 44 (46) (orwhen such a request is generated by the electronic control unit 40itself), the electronic control unit 40 provides for driving theactuator 16 (17) to displace the chain along axis A (B) in the seconddirection until the counter 47 (48) reaches the logic value (readdirectly from the storage means 49 (50) or derived from the informationread from the storage means 49 (50)) associated with the adjacentsprocket 11 (12), with immediately smaller diameter. The chain 13 isthen at the adjacent sprocket 11 (12), with immediately smallerdiameter.

In the case in which the actuators 16, 17 include stepper motors, amovement of one step or an integer multiple of steps of the steppermotor, in a first or second direction of rotation, corresponds to eachunitary increase or decrease of the counter 47, 48.

Making reference to FIG. 3, a first embodiment of the storage means isshown. The rear and front storage means 49 and 50 directly store a logicvalue associated with each sprocket 11, 12 of the respective gearshiftgroup 9, 10. Thus, in the exemplifying case of rear gearshift group 9comprising ten sprockets or pinions 11, the rear storage means 49 aresuitable for storing a logic value R1 associated with the sprocket withthe smallest diameter, a logic value R2 associated with the secondsprocket, logic value R3 associated with the third sprocket, etc., up toa logic value R10 associated with the sprocket with the largestdiameter; in the exemplifying case of front gearshift group 10comprising two sprockets or crowns 12, the front storage means 50 aresuitable for storing a logic value F1 associated with the sprocket withthe smallest diameter and a logic value F2 associated with the sprocketwith the largest diameter.

In this first embodiment, the electronic control unit 40 determines thelogic values which the counters 47, 48 must assume so that thederailleurs 14, 15 are positioned as desired with respect to sprockets11, 12 by reading the associated logic value directly from the memory49, 50.

Making reference to FIG. 4, a second embodiment of the storage means49,50 is shown. The rear storage means 49 stores a differential amountassociated with each pair of adjacent sprockets 11. Thus, in theexemplifying case of rear gearshift group 9 comprising ten sprockets orpinions 11, the rear storage means 49 are suitable for storing adifferential amount ΔR1-2 associated with the pair consisting of thesprocket 11 with the smallest diameter and the second sprocket 11immediately adjacent to it (with a slightly larger diameter), adifferential amount ΔR2-3 associated with the pair consisting of thesecond and third sprockets, etc., up to a differential amount ΔR9-10associated with the pair of sprockets 11 having the largest diameters;in the exemplifying case of front gearshift group 10 comprising twosprockets or crowns 12, the front storage means 50 are suitable forstoring a single differential amount ΔF1-2.

In this embodiment, the electronic control unit 40 determines the logicvalues which the counters 47, 48 must assume so that the derailleurs 14,15 are positioned as desired with respect to sprockets 11, 12 by adding(or subtracting) the differential amount corresponding to the pairconsisting of the current sprocket 11, 12 and the sprocket 11, 12 withimmediately larger (or smaller) diameter stored in the memory 49, 50 to(or from) the current value of the counter.

When the gearshift groups 9, 10 including sprockets 11, 12 are equallyspaced by a certain pitch, the rear storage means 49 and front storagemeans 50 (FIG. 5) are suitable for storing a single differential amountΔR and ΔF. If the pitch between adjacent sprockets 11 of the reargearshift group 9 is equal to the pitch between adjacent sprockets 12 ofthe front gearshift group 10, there may be only a single storage means,for example just the front memory 49.

According to the invention, the electronically servo-assisted gearshiftsystem 8, and in particular its electronic control unit 40, is capableof operating, in a normal ride operating mode, or other operating modes,including a programming mode of the electronic control unit, adiagnostics mode, a “choice-of-operation mode” in which it is possibleto choose between manual, automatic or semi-automatic control of thegearshift system 8, for example as described in document U.S. Pat. No.5,865,454, an adjustment mode and, according to a preferred embodimentof the invention, a setting mode. The programming, diagnostics andchoice-of-operation modes are not described in detail since they are notpart of the present invention.

The various operating modes are selected through manual mode selectioncommand means, forming a user interface with the electronic control unit40, preferably in cooperation with the display unit 60. The manual modeselection command means preferably includes two buttons 61, 62, locatedon the display unit 60. The user interface can of course include otherbuttons or levers, such as the button 63, at the display unit 60 and/orat the grips of the handlebar 70, used in the other operating modes. Forexample, when the rider presses the button 61 shown under the displayunit 60, the electronic control unit 40 can show on the display unit 60the various operating modes in cyclical sequence and the mode selectionmeans can include the same button 61 for accepting the operating modecurrently displayed on the display unit 60 and a button, for example thebutton 62, shown to the right of the display unit 60, to not accept itand cause the display of the next operating mode.

Preferably, however, the adjustment mode of the gearshift system 8,instead of being shown together with the other operating modes, canimmediately be reached from normal travel mode, for example through aquick double press of the button 61, holding down the button 61, orpressing a further dedicated button (not shown).

Alternatively, the electronic control unit 40 can show on the displayunit 60 a menu containing all the various operating modes, and the modeselection means can include a button for scrolling a selection cursorcyclically in the menu, or two buttons to scroll the selection cursor inthe menu in the two directions, as well as a button for accepting theoperating mode upon which the selection cursor is currently displayed.

The buttons for selecting an operating mode, or the buttons forscrolling the cursor, may be the same upwards and downwardsgear-shifting levers 43, 44 or 45, 46, the electronic control unit 40interpreting the signal generated by the pressing of the leversaccording to the context, for example through logic gates or Booleanfunctions.

In any case, it is preferred that the activation button of theadjustment mode be physically arranged at the display unit 60 (and notat one of the grips of the handlebar 70) to avoid accidental activationof such an operating mode.

A flow chart exemplifying the mode selection of the gearshift system 8according to the invention is presented in FIG. 6.

When power is switched on 101, the electronic control unit 40 operatesin control ride mode 102 which allows manual operation. The systemremains in this mode, in which it waits for and controls the signalscoming from the gearshifting levers 43-46 in the way above described,negatively answering a query block 103 querying whether to change theoperating mode. The query block 103 monitors a mode selection requestsignal generated by pressing the button 61.

In parallel, in a block 116, an adjustment operating mode requestsignal, for example generated in the way above described (holding downthe button 61, etc.), is monitored by the electronic control unit 40.Upon receipt of the adjustment operating mode request signal, theelectronic control unit controls an adjustment operating mode 117,better described hereafter with reference to FIG. 9.

If the mode selection request signal is activated, the electroniccontrol unit 40 queries in a block 104 whether one wishes to enter intoa programming mode and, in the affirmative case, controls such a mode ina block 105 remaining there until it receives a negative answer to ablock 106 requesting whether one wishes to continue, returning to theblock 102 for controlling the normal ride operating mode. In the case ofa negative answer to the block 104, the electronic control unit 40queries in a block 107 whether one wishes to enter into a diagnosticsmode and, in the affirmative case, controls such a mode in a block 108remaining there until it receives a negative answer to a block 109requesting whether one wishes to continue, returning to the block 102for controlling the normal ride operating mode. In the case of anegative answer to the block 107, the electronic control unit 40 queriesin a block 110 whether one wishes to enter into the aforementionedoperation selection mode and, in the affirmative case, controls such amode in a block 111 remaining there until it receives a negative answerto a block 112 requesting whether one wishes to continue, returning tothe block 102 for controlling the normal ride operating mode, inparticular in manual, semi-automatic or automatic operation as chosen bythe rider.

A request 113 whether one wishes to enter into a setting mode is nestedwithin block 111, so that two confirmations are requested from the userto avoid such a setting mode being selected by mistake. In the case of anegative answer to the block 113, there is a return to block 111. In thecase of an affirmative answer to the block 113, the electronic controlunit 40 controls a setting operating mode 114, better describedhereafter with reference to FIGS. 7 and 8, remaining there until itreceives a negative answer to a block 115 request whether one wishes tocontinue or cause a return to block 111.

FIGS. 7 and 8 jointly illustrate a flow chart of the setting operatingmode 114. In these figures the rear derailleur 14 is indicated as“gearshift”, and the front derailleur 15 is indicated as “derailleur”.

Starting from an initial block 200, in a block 201, the electroniccontrol unit 40 checks if it is already in the setting mode of the reargearshift group 9, referring to a gearshift setting mode flag. In thenegative case, in a block 202 it is queried whether one wishes toactivate the setting mode of the rear gearshift group 9 and, in thenegative case, the setting mode, as far as the rear gearshift group 9 isconcerned, terminates at a block 203. The block 203 corresponds to thestart block 300 of the setting mode of the front gearshift group 10illustrated in FIG. 8. The setting mode of the front gearshift group iscompletely analogous to the setting mode of the rear gearshift group andneed not be further described herein.

In the case of an affirmative answer to block 202, the gearshift settingmode flag is set and the flow proceeds according to blocks 203/300, 301and 302 (which provide a negative answer since the setting of the reargearshift group 9 is being carried out), then returning to the initialblock 200 (through block 115 of FIG. 6).

In block 201 since the setting mode flag is set, the gearshift settingmode is active, and the electronic control unit 40 queries in a block205 whether one wishes to deactivate the gearshift setting mode.

In the negative case, the electronic control unit 40 determines in ablock 206 whether the upwards gear-shifting request lever 43 has beenpressed.

In the affirmative case, the electronic control unit 40 in a block 207drives the rear actuator 16 so that it moves the chain in the directiontowards the larger diameter sprocket(s) and thus continues to drive therear actuator 16 in this way so long as the upwards gear-shiftingrequest lever 43 remains pressed, as determined by a block 208. The rearactuator 16 is driven so as to displace the rear derailleur 14 by smalldistances, in any case smaller than the distance between two adjacentsprockets 11. Preferably, to allow more precise adjustment, the rearactuator 16 is driven at a low speed. In particular, in the case inwhich the rear actuator 16 comprises a stepper motor, this is driven tomove by one step at a time or, if one wishes to obtain a fasteradjustment, by a certain number of steps at a time.

When the upwards gear-shifting request lever 43 is no longer pressed,the actuator is stopped in a block 209 and there is a return to block205, in which the electronic control unit 40 queries whether one wishesto deactivate the gearshift setting mode.

If the electronic control unit 40 determines in block 206 that theupwards gear-shifting request lever 43 has not been pressed, it checksin a block 210 whether the downwards gear-shifting request lever 44 hasbeen pressed.

In the affirmative case, the electronic control unit 40, in a block 211,drives the rear actuator 16 (to displace the rear derailleur 14 inincrements smaller than the distance between two adjacent sprockets 11,preferably, at a low speed (by one or more steps at a time when astepper motor is employed). Therefore, the chain is displaced in adirection towards the smaller diameter sprocket(s). The rear actuator 16is driven in this way so long as the downwards gear-shifting requestlever 44 remains pressed, as checked in a block 212.

When the downwards gear-shifting request lever 44 is no longer pressed,the actuator is stopped in a block 213 and there is a return to block205, in which the electronic control unit 40 queries whether one wishesto deactivate the gearshift setting mode.

If in block 205 the electronic control unit 40 receives a positiveanswer, in a block 214 it cancels the gearshift setting mode flag and,in a block 215, sets a biunique correspondence between the currentphysical position of the rear actuator 16, as determined by thetransducer 18, and the logic value associated with the gear ratiorelative to the sprocket 11 upon which the setting mode has been carriedout.

In the preferred embodiment, in which the electronic control unit 40includes the rear counter 47, the setting of the biunique correspondenceis accomplished by setting the value of the rear counter 47 to the logicvalue associated with the sprocket upon which the setting is carriedout, read or determined from the storage means 49.

The sprocket 11 upon which the setting mode is carried out is normallythe one with the smallest diameter, but it can be programmed to choosethe sprocket upon which to carry out the setting mode. In such a case,the electronic control unit 40 queries the user to specify the sprocket11 upon which the setting mode is carried out or has been carried out,for example before block 204 or before block 215.

Therefore, with respect to the first embodiment of the storage meansillustrated in FIG. 3, the value of the counter 47 is set to value R1 orto one of values R1, R2, . . . or R10, according to which of thesprockets 11 is chosen for the setting.

In the alternative embodiment of the storage means illustrated in FIG.4, the counter 47 is zeroed when the sprocket 11 chosen for setting isthe one with the smallest diameter. If the sprocket chosen for settingis the i-th wheel of the gearshift group, the value of the counter 47 isset to the value determined by the differential amount ΔR(i−1)−iassociated with the pair consisting of one of the sprockets 11 chosenfor setting and the other one of sprockets 11 with immediately smallerdiameter, added to all the differential amounts associated with any pairof smaller diameter sprockets. In other words, in the case in which thesetting is carried out on the second sprocket 11, the value of thecounter 47 shall be set to ΔR1-2, in the case in which the setting iscarried out on the third sprocket 11, the value of the counter 47 shallbe set to ΔR1-2+ΔR2-3 etc.

In the alternative embodiment of the storage means illustrated in FIG.5, the counter 47 shall be zeroed when one of the sprockets 11 chosenfor setting is the one with the smallest diameter. If the sprocketchosen for setting is the i-th wheel of the gearshift group, the valueof the counter 47 shall be set to the value determined by thedifferential amount ΔR multiplied by i−1, in other words by the numberindicating the position of the sprocket chosen for setting in the reargearshift group 9, less one. In other words, in the case in whichsetting is carried out on the second of sprockets 11, the value of thecounter 47 shall be set to ΔR, in the case in which setting is carriedout on the third sprocket 11, the value of the counter 47 shall be setto ΔR*2, etc.

In another alternative embodiment, the setting of the biuniquecorrespondence can be accomplished by modifying the logic value R1, R2,. . . R10, F1, F2 (or, with the appropriate calculations, the values ofthe differential amounts ΔRx, ΔFy) of the storage means 49 associatedwith the sprocket on which the setting is carried out, based upon thevalue of the rear counter 47. Should it be permitted to modify the logicvalues associated with the sprockets in this way, it shall beappropriate to provide for the possibility of returning to the defaultlogic values (corresponding to nominal or average values), suitablystored in read only storage means.

The setting mode 114 is preferably carried out in a workshop with thebicycle mounted on a stand.

A first procedure is that of holding the bicycle still, manually movingexclusively the actuator 16 up and down and stopping, in other wordscoming out from the setting operating mode, when one believes to haveobtained the optimal alignment “by sight”.

The alignment by sight can be improved with different provisions bothmechanical and electronic. One can, for example, mount a plate on one ofthe small idle sprockets of the rear derailleur 14 (and/or on the frontderailleur 15), so that there is alignment when it touches the sprocket11 (12) with the smallest diameter or in any case the one predeterminedfor setting. Or else, on the small sprocket a laser diode can be mountedand on the sprocket 11 (12) a laser light receiver can be mounted, orvice-versa. To further improve alignment, one could exploit “lighttriangulation”, etc.

A second procedure is that of actuating the chain through the pedalcrank unit 7 and verifying the alignment “by sound”. An expert user,indeed, can understand that with best alignment there is also minimumnoisiness.

Clearly, one can combine the two procedures and make the alignment usingboth sight and sound.

It is possible to add a step in which (during the normal ride operatingmode) the gearshift system 8 is adjusted through a complete range ofupwards travel (and/or a complete range of downwards travel), whilesimultaneously performing inspection by sight and/or by sound. At theend of the complete range of travel(s) (returning to setting mode) thesetting is “refined”. Thus, operation can be carried out manually by theoperator, or else automatically by the electronic control unit 40. Ofcourse, if just one complete travel is carried out, the setting shallthen be “refined” on a different sprocket from the one upon which theinitial setting was carried out.

It is also possible to carry out an automatic or semi-automatic setting,providing for sensors (not shown) of the relative position between thederailleur 14, 15 and the sprocket 11, 12 chosen for setting. Suchrelative position sensors can for example include a collimated lightsource and a photodetector respectively associated with the derailleur14, 15 and with the sprocket 11, 12. When the photodetector detects thelight emitted from the collimated light source, it transmits informationto the electronic control unit 40 on the desired alignment,corresponding to the positive outcome of block 205 (305) requestingwhether one wishes to deactivate the gearshift setting mode. In the casein which the photodetector has a certain extension in the axialdirection of the sprocket 11, 12, like for example in the case of alinear CCD sensor, it can also identify, according to the point in whichit receives the light coming from the collimated light source, what isthe displacement direction necessary for reaching alignment, sendingcorresponding signals to the electronic control unit 40. Such signalscorrespond to the positive outcome of blocks 206, 208, 210, 212 (306,308, 310, 312) which determine whether the upwards or downwardsgear-shifting request lever has been pressed.

FIG. 9 illustrates a flow chart exemplifying the adjustment operatingmode 117 according to the invention.

Starting from an initial block 400, in a block 401 the electroniccontrol unit 40 queries whether one wishes to proceed to the adjustmentof the rear gearshift group 9 (indicated simply with “gearshift” in thefigures) or to the adjustment of the front gearshift group 10 (indicatedsimply with “derailleur” in the figures).

In the case in which the user confirms proceeding to the adjustment ofthe rear gearshift group 9 (left output from the block 401), in a block402 the automatic control unit 40 waits to receive an upwardsdisplacement request signal or a downwards displacement request signal.Such signals are preferably provided through the levers 43, 44 used forupwards and downwards gear-shifting request in the normal ride operatingmode.

In the case in which the rider presses the lever 43, the automaticcontrol unit 40 receives the upwards displacement request signal (leftoutput “+” from block 402). The electronic control unit 40 then checks,in a block 403, whether a maximum upwards displacement has been reached.In the negative case, the system provides, in a block 404, forincreasing the value of a rear adjustment variable R-OFFSET, stored in asuitable memory, and, in a block 405, for driving the motor of the rearactuator 16 to carry out a displacement of the rear derailleur 14 whichis small enough, in any case smaller than the distance between twoadjacent sprockets 11.

In the case in which the check of block 403 gives a positive outcome,i.e. if the maximum upwards displacement has been reached, the step 404of increasing the rear adjustment variable R-OFFSET and the step 405 ofdriving the actuator 16 are not carried out.

The electronic control unit 40 then checks in a block 406 whether onewishes to deactivate the adjustment mode, deemed to be completed, forexample monitoring the pressing of button 61 of the display unit. In thepositive case, the adjustment mode terminates at a block 407. In absenceof such an adjustment mode deactivation signal, block 402 monitoring thepressing of the levers 43, 44 is returned to.

Analogously, if the pressing of the lever 44 is detected, i.e. if theelectronic control unit 40 receives a downwards displacement requestsignal (right output “−” from block 402), the electronic control unit 40checks, in a block 408, whether a maximum downwards displacement hasbeen reached. In the negative case, the system provides, in a block 409,for decreasing the value of the rear adjustment variable R-OFFSET, and,in block 405, for driving the motor of the rear actuator 16. In the casein which the check of block 408 gives a positive outcome, i.e. if themaximum downwards displacement has been reached, the step 409 ofdecreasing the rear adjustment variable R-OFFSET and the step 405 ofdriving of the actuator 16 are not carried out.

The execution then proceeds in block 406 of checking whether one wishesto deactivate the adjustment mode, described above.

In the case in which the user wishes to proceed with the adjustment ofthe front gearshift group 10 (right output from block 401), the stepsrepresented by blocks 410-416 will be carried out, to which thedescription of the blocks 402-409 analogously applies. In particular, inblocks 412 and 416 the value of a front adjustment variable F-OFFSETshall be updated (increased or decreased).

The front and rear adjustment variables R-OFFSET and F-OFFSET have adefault value equal to zero, and are brought again to such a value equalto zero at the end of the setting mode, where provided for, or through asuitable command provided by the user.

The values of the front and rear adjustment variables R-OFFSET andF-OFFSET, set in the adjustment operating mode described above,condition the electronic control unit 40 during the normal rideoperating mode in the following way.

In the case in which the front and rear adjustment variables R-OFFSETand F-OFFSET are different from zero, the logic values which thecounters 47, 48 must assume so that the derailleurs 14, 15 arepositioned at the desired sprockets 11, 12 (read directly from thememory 49, 50 in the embodiment of FIG. 3 or derived from thedifferential amounts in the embodiments of FIGS. 4 and 5 in the waydescribed above) are modified algebraically summing (i.e. adding orsubtracting) thereto the value of the rear adjustment variable R-OFFSETor the value of the front adjustment variable F-OFFSET, respectively.

By way of an example, for a upwards gear-shifting of the rear gearshiftgroup 9 from the third sprocket 11 to the fourth sprocket 11, in thecase of the embodiment of FIG. 3 the electronic control unit 40 shalldrive the motor of the rear actuator 16 until the rear counter 47reaches the value R3+R-OFFSET (where R-OFFSET can have a negativevalue). In the case of the embodiment of FIG. 4, the electronic controlunit 40 shall drive the motor of the rear actuator 16 until the rearcounter 47 reaches the value ΔR1-2+ΔR2-3+R-OFFSET (where R-OFFSET canhave a negative value), and in the case of the embodiment of FIG. 5,until the rear counter 47 reaches the value 2*ΔR+R-OFFSET.

The adjustment operating mode can be activated whatever the current gearratio, in other words on whatever sprocket 11 or 12. The rider may alignthe chain on the chosen sprocket “by ear” with the bicycle in motion todetermine the adjustment variable. It is also possible to provide, in ananalogous manner to that which was described for the setting operatingmode, visual aid instruments (such as the plate mounted on thederailleur) and instruments for automatic alignment check and/orautoalignment instruments (such as the laser diode-photodetector pair).

Since small misalignments between the derailleur 14 or 15 and a sprocket11 or 12 have to be compensated for, the maximum upwards and downwardsdisplacement values checked in blocks 403, 408, 411, 415, preferablycorrespond to half the pitch between two adjacent sprockets 11 or 12(distance in the direction of axis A or B). In the case in which thesprocket 11 or 12 on which the adjustment is carried out is the one withthe smallest diameter or the one with the largest diameter of therespective gearshift group 9, 10, the maximum displacement is preferablysmaller than half the pitch, in order to avoid an impact of the motorsof the actuators 16, 17 and/or of the derailleurs 14, 15 againstmechanical ends of stroke stops or a dangerous approach to the spokes ofthe rear wheel 4.

The displacement of the derailleur 14, 15 in the adjustment operatingmode is preferably carried out at low speed, through a movement of onestep at a time, or more preferably by a certain number of steps at atime as in the case where a stepper motor is employed. If, for example,the displacement between two adjacent sprockets (gear-shifting) requires100 steps of the stepper motor, in the adjustment mode the stepper motorof the actuator 16, 17 can be driven for 5-8 steps at a time, so that10-6 upwards (downwards) displacement request signals are necessary todisplace the chain by the aforementioned maximum displacement (half thedistance between two adjacent wheels).

In the setting operating mode 114, where provided for, the stepper motorof the actuator 16, 17 can, on the other hand, be driven by just one ortwo steps at a time.

In such a way, the setting operating mode 114 can be carried outperiodically, in a workshop, dedicating all the necessary time andobtaining a very precise result, i.e. a fine adjustment. The adjustmentoperating mode 117 shall be carried out when there is less timeavailable, in particular during cycling races and even whilst moving,obtaining a faster adjustment.

Analogously to what has been described with reference to the settingoperating mode, it is possible to add a step in which (going in thenormal ride operating mode) the gearshift system 8 is made to make acomplete upwards and/or downwards travel, in the mean time carrying outa check by sight and/or by ear. At the end of the complete travel(s)(returning to the adjustment mode) the adjustment is further “refined”.Such a step can be carried out manually by the operator, or elseautomatically by the electronic control unit 40.

It is also possible to provide for, instead of a single adjustmentvariable for each gearshift group 9, 10, an adjustment variable for eachsprocket 11, 12 of each gearshift group 9, 10 (for example, R-OFFSET-1,R-OFFSET-2, . . . , R-OFFSET-10; F-OFFSET-1, F-OFFSET-2).

The microprocessor(s) of the electronic control unit 40 can, forexample, be made in C-MOS technology, which has the advantage of havinglow power consumption.

As an alternative to implementation through dedicated hardware, thefunctionalities of the electronic control unit 40 described above can beaccomplished by a software program loadable in a small computer.

In another aspect thereof, the invention concerns a program forelectronically servo-assisting a bicycle gearshift, comprising programcode means suitable for carrying out the steps of the method abovedescribed when the program is run on a computer. The program ispreferably embodied in at least one microcontroller. Alternatively, theprogram can be stored in a computer memory or embodied in a read-onlymemory. In yet another embodiment thereof, the invention concerns anelectronic circuit suitable for carrying out the steps of the methodabove described.

In another alternative embodiment, the adjustment operating mode 117and/or the setting mode 114 can be implemented by a second electronicboard separate from a first electronic control board which controls thegearshift system 8 in the normal ride operating mode 102 and optionallythe other operating modes. The setting mode 114 may also be implementedby a software program separate from a control program which controls thegearshift system 8 in the normal ride operating mode and, optionally,the other operating modes. By using a software procedure, the adjustmentoperating mode 117 and/or the setting mode 114 can be provided as anupdate to existing servo-assisted gearshifts.

1. A method for controlling an electronically servo-assisted bicyclegearshift, comprising the steps of: a) driving an actuator of a bicyclegearshift to displace a chain of the gearshift in a chosen axialdirection with respect to a gearshift group having a plurality ofsprockets including at least two adjacent sprockets; b) receivinginformation in a control unit on a desired alignment between the chainand a predetermined sprocket of the gearshift group; and c) setting anadjustment variable common to all gear ratios of the gearshift group, ina control unit, of a logic value associated with a gear ratio relativeto the predetermined sprocket to a value corresponding to thedisplacement carried out in step a) of driving the actuator.
 2. A methodfor controlling an electronically servo-assisted bicycle gearshift,comprising the steps of: a) driving an actuator of a bicycle gearshiftto displace a chain of the gearshift in a chosen axial direction withrespect to a gearshift group having a plurality of sprockets includingat least two adjacent sprockets; b) receiving information in a controlunit on a desired alignment between the chain and a predeterminedsprocket of the gearshift group; c) setting an adjustment variable, in acontrol unit, of a logic value associated with a gear ratio relative tothe predetermined sprocket to a value corresponding to the displacementcarried out in step a) of driving the actuator; d) receiving adisplacement request signal of the actuator in the chosen direction,wherein in step a) of driving the actuator, the displacement of thechain is carried out in accordance with the displacement request signalreceived in step d); wherein step d) of receiving a displacement requestsignal and step a) of driving the actuator are repeated until receivingthe information on the desired alignment in step b); and e)subordinating a repetition of step a) of driving the actuator to checkthat the displacement carried out in step a) has not reached a maximumdisplacement value.
 3. The method of claim 2, wherein the adjustmentvariable is one of a plurality of adjustment variables, each associatedwith a gear ratio.
 4. The method of claim 2, wherein the maximumdisplacement value is lower than half a distance between the twoadjacent sprockets of the gearshift group if the predetermined sprocketis a sprocket with the largest or smallest diameter, respectively, ofthe gearshift group, otherwise it is equal to half the distance betweentwo adjacent sprockets of the gearshift group.
 5. A method forcontrolling an electronically servo-assisted bicycle gearshift,comprising the steps of: a) driving an actuator of a bicycle gearshiftto displace a chain of the gearshift in a chosen axial direction withrespect to a gearshift group having a plurality of sprockets includingat least two adjacent sprockets; b) receiving information in a controlunit on a desired alignment between the chain and a predeterminedsprocket of the gearshift group; c) setting an adjustment variable, in acontrol unit, of a logic value associated with a gear ratio relative tothe predetermined sprocket to a value corresponding to the displacementcarried out in step a) of driving the actuator; d) receiving adisplacement request signal of the actuator in the chosen direction,wherein in step a) of driving the actuator, the displacement of thechain is carried out in accordance with the displacement reuuest signalreceived in step d); wherein step d) of receiving a displacement requestsignal and step a) of driving the actuator are repeated until receivingthe information on the desired alignment in step b); f) receiving anoperating mode signal selected from the group comprising at least anormal ride operating mode and an adjustment operating mode; and g)receiving a displacement request signal of the actuator to displace thechain in the chosen axial direction with respect to the gearshift group;h1) wherein when the operating mode signal corresponds to the adjustmentoperating mode, at least steps a)-c) are carried out; and h2) whereinwhen the operating mode signal corresponds to the normal ride operatingmode, the step of driving the actuator of the gearshift to displace thechain of the gearshift in the chosen axial direction with respect to thegearshift group, between a position corresponding to a first sprocket ofthe gearshift group and a physical position corresponding to a secondsprocket of the gearshift group is carried out, the physical positionsbeing determined by the logic values associated with the sprockets asadjusted by the adjustment variable.
 6. The method of claim 5, whereinstep h2) further comprises driving the actuator to displace the chain inthe chosen axial direction a distance determined by modifying a value ofa counter by an amount equal to an algebraic sum of a common adjustmentvariable or the adjustment variable associated with the gear ratiorelative to the second sprocket and a difference between the logicvalues associated with the second sprocket and with the first sprocket.7. The method of claim 6, wherein the difference between the logicvalues associated with the second sprocket and with the first sprocketis indicated by at least one differential amount pre-associated witheach pair of adjacent sprockets of the gearshift group.
 8. The method ofclaim 5, wherein the operating mode signal is selected from the groupalso consisting of a setting operating mode, and further comprising thestep of: h3) when the operating mode signal corresponds to the settingoperating mode, carrying out the steps of; h31) driving the actuator todisplace the chain (13) of the gearshift in the chosen axial directionwith respect to the gearshift group; h32) receiving information on thedesired alignment between the chain and a predetermined sprocket of thegearshift group; h33) setting a biunique correspondence between aphysical position of the actuator at step h32) and a logic valueassociated with the gear ratio relative to the predetermined sprocket;and h34) zeroing the adjustment variable(s).
 9. The method of claim 8,wherein the predetermined sprocket in step h3) is the a sprocket withthe a smallest diameter of the sprockets in the gearshift group.
 10. Themethod of claim 8, wherein the step h33) of setting a biuniquecorrespondence comprises setting a value of a counter to said logicvalue pre-associated with the predetermined sprocket.
 11. The method ofclaim 10, wherein the step h33) of setting a biunique correspondencecomprises zeroing the counter.
 12. The method of claim 8, wherein thestep h33) of setting a biunique correspondence comprises storing instorage means a current value of a counter as the logic valuepre-associated with the predetermined sprocket.
 13. The method of claim12, wherein the step h3) is repeated for each sprocket and acorresponding logic value.
 14. A method for controlling anelectronically servo-assisted bicycle gearshift, comprising the stepsof: a) driving an actuator of a bicycle gearshift to displace a chain ofthe gearshift in a chosen axial direction with respect to a gearshiftgroup having a plurality of sprockets including at least two adjacentsprockets; b) receiving information in a control unit on a desiredalignment between the chain and a predetermined sprocket of thegearshift group; c) setting an adjustment variable, in a control unit,of a logic value associated with a gear ratio relative to thepredetermined sprocket to a value corresponding to the displacementcarried out in step a) of driving the actuator; d) receiving adisplacement request signal of the actuator in the chosen direction,wherein in step a) of driving the actuator, the displacement of thechain is carried out in accordance with the displacement request signalreceived in step d); j) providing means for detecting a relativeposition between the chain and the predetermined sprocket and providingthe information on the desired alignment.
 15. The method of claim 14,wherein the means for detecting the relative position between the chainand the predetermined sprocket is also suitable for providing thedisplacement request signal of the actuator.
 16. A method forcontrolling an electronically servo-assisted bicycle gearshift,comprising the steps of: a) driving an actuator of a bicycle gearshiftto displace a chain of the gearshift in a chosen axial direction withrespect to a gearshift group having a plurality of sprockets includingat least two adjacent sprockets; b) receiving information in a controlunit on a desired alignment between the chain and a undeterminedsprocket of the gearshift group; c) setting an adjustment variable, in acontrol unit, of a logic value associated with a gear ratio relative tothe predetermined sprocket to a value corresponding to the displacementcarried out in step a) of driving the actuator; k) driving the actuatorof the gearshift to displace the chain of the gearshift in the chosenaxial direction with respect to the gearshift group, from an initialposition sequentially to each adjacent sprocket of the gearshift group;and m) receiving second information on the desired alignment between thechain and a predetermined sprocket of the gearshift group.
 17. Themethod of claim 16, further comprising the step of: k1) driving theactuator of the gearshift to displace the chain of the gearshift in thechosen axial direction with respect to the gearshift group sequentiallyat each adjacent sprocket of the gearshift group up to the predeterminedsprocket.
 18. A method for controlling an electronically servo-assistedbicycle gearshift, comprising the steps of: a) driving an actuator of abicycle gearshift at a plurality of operating speeds to displace a chainof the gearshift in a chosen axial direction with respect to a gearshiftgroup having a plurality of sprockets including at least two adjacentsprockets; b) receiving information in a control unit on a desiredalignment between the chain and a predetermined sprocket of thegearshift group; and c) setting an adjustment variable, in a controlunit, of a logic value associated with a sear ratio relative to thepredetermined sprocket to a value corresponding to the displacementcarried out in step a) of driving the actuator.
 19. A method forcontrolling an electronically servo-assisted bicycle gearshift,comprising the steps of: a) driving an actuator of a bicycle gearshiftto displace a chain of the gearshift in a chosen axial direction withrespect to a gearshift group having a plurality of sprockets includingat least two adjacent sprockets; b) receiving information in a controlunit on a desired alignment between the chain and a predeterminedsprocket of the gearshift group; c) setting an adjustment variable, in acontrol unit, of a logic value associated with a gear ratio relative tothe predetermined sprocket to a value corresponding to the displacementcarried out in step a) of driving the actuator; and n) selectivelydriving a stepper motor of the actuator by a first set number of stepsand selectively driving the stepper motor by a second set number ofsteps greater than the first set number of steps to displace the chain.20. A bicycle gearshift comprising: a rear actuator and a front actuatorhaving a respective motor to displace, through a guide element, a chainin an axial direction with respect to a respective gearshift groupcomprising at least two sprockets respectively associated with a hub ofa rear wheel and with an axle of pedal cranks of a bicycle, in aselected direction; manual input means comprising means for entering asignal requesting displacement of a selected actuator, respectively, inthe selected direction; and an electronic control unit connected to theinput means, to the rear actuator and to the front actuator, operating,in a normal ride operating mode, to drive the selected actuator,respectively, based upon the displacement request signal to displace thechain from a first sprocket to a second adjacent sprocket of therespective gear-shift group; wherein the manual input means comprisesmeans for selecting operating mode at least between said normal rideoperating mode and an adjustment operating mode; wherein the electroniccontrol unit, in the normal ride operating mode, drives the selectedactuator, between a logic value associated with the first sprocket and alogic value associated with the second sprocket, modified by a value ofan adjustment variable; and wherein the electronic control unit isoperative, in the adjustment operating mode, to drive the selectedactuator based upon the displacement request signal to displace thechain in the selected direction and to increase or decrease the value ofthe adjustment variable the electronic control unit also having meansfor inputting information on the desired alignment between the chain anda predetermined sprocket of the gearshift group to switch from theadjustment operating mode to the normal ride operating mode.
 21. Thegearshift of claim 20, wherein the adjustment variable is common to allthe gear ratios of the gearshift group.
 22. The gearshift of claim 20,wherein the adjustment variable is one of a plurality of adjustmentvariables, each associated with a gear ratio.
 23. The gearshift of claim20, wherein the electronic control unit comprises at least one counter,means for updating the counter during the driving of the selectedactuator and means for comparing the value of the counter with logicvalues.
 24. The gearshift of claim 23, wherein the rear and frontactuators include stepper motors, and a displacement of the selectedactuator corresponds to a unitary increase or decrease of the at leastone counter.
 25. The gearshift of claim 23, wherein the operating modes,which can be selected by the operating mode selection means, furthercomprise a setting operating mode and in that the electronic controlunit is operative, in the setting operating mode, to drive the selectedactuator based upon the displacement request signal to displace thechain in the selected direction, the electronic control unit also havingmeans for inputting information on the desired alignment between thechain and a predetermined sprocket of the gearshift group, and means,responsive to the means for inputting information on the desiredalignment, for setting a biunique correspondence between a physicalposition of the selected actuator, respectively, and a logic valueassociated with the predetermined sprocket.
 26. The gearshift of claim25, wherein: the means for setting a biunique correspondence comprisesmeans for setting the value of the at least one counter to the logicvalue pre-associated with the predetermined sprocket.
 27. The gearshiftof claim 26, wherein the predetermined sprocket is the sprocket with isa smallest diameter and the means for setting a biunique correspondencecomprises means for zeroing a rear or front counter.
 28. The gearshiftof claim 25, wherein: the means for setting a biunique correspondencecomprises means for storing in storage means a current value of thecounter as the logic value pre-associated with the predeterminedsprocket.
 29. The gearshift of claim 20, further comprising means forstoring a differential amount pre-associated with each of the at leasttwo adjacent sprockets, wherein in the normal ride operating mode thelogic value associated with the second sprocket is determined by addingthe differential amount pre-associated with the pair formed by the firstand second sprocket to the logic value associated with the firstsprocket.
 30. The gearshift of claim 29, wherein the differentialamounts pre-associated with each pair of adjacent sprockets of thegearshift group are equal to each other.
 31. The gearshift of claim 20,further comprising at least one transducer for detecting a, physicalposition of the selected actuator and providing it to the electroniccontrol unit.
 32. The gearshift of claim 31, wherein in the normal rideoperating mode, the electronic control unit drives the selected actuatorto displace the chain between the first sprocket and the second sprocketfeedback controlled by a physical position detected by the at least onetransducer.
 33. The gearshift of claim 31, wherein the transducerincludes means for detecting a relative position between the selectedactuator, and the predetermined sprocket and for generating theinformation on the desired alignment.
 34. The gearshift of claim 33,wherein the transducer is further suitable for generating thedisplacement request signal of the actuator.
 35. The gearshift of claim33, wherein the means for detecting the relative position comprises acollimated light source and a collimated light sensor, cooperativelypositioned at the actuator and at the predetermined sprocket.
 36. Thegearshift of claim 20, further comprising means for outputtinginformation defining, with the manual input means, a user interface withthe electronic control unit.
 37. The gearshift of claim 20, furthercomprising a power board arranged between the electronic control unitand the rear and front actuators.
 38. The gearshift of claim 20, whereinthe electronic control unit comprises at least one microcontroller madein C-MOS technology.
 39. The gearshift of claim 20, wherein theelectronic control unit is distributed and comprises manymicrocontrollers at a display unit and at a unit controlling the manualinput means and at a power board.
 40. A method for providing anadjustment operating mode of an electronic control unit for aservo-assisted bicycle gearshift system comprising: determining whethera gearshift displacement request is received; determining whether amaximum displacement has been achieved; moving a gearshift to provide adisplacement of the gearshift to achieve a desired physical gearshiftposition; and modifying a value of an adjustment variable, for modifyinga logic value associated with a predetermined gear ratio, to beproportional to the displacement of the gearshift.
 41. The method ofclaim 40, wherein the step of moving the gearshift include the step ofactuating an actuator.
 42. The method of claim 40, further comprisingdetermining a desired physical gearshift position using a positiontransducer.
 43. The method of claim 40, further comprising storing thevalue of the adjustment variable in a memory of the electronic controlunit.
 44. A bicycle gearshift system comprising: at least one actuatorfor displacing a transmission element from a first to at least a secondsprocket; at least a first input device for entering a displacementrequest signal and for selecting between operating modes; an electroniccontrol unit, for driving the actuator, in a first operating mode, inresponse to the displacement request signal, between a first logicvalue, as modified by an adjustment variable, associated with the firstsprocket and at least a second logic value, as modified by theadjustment variable, associated with the second sprocket; and, in asecond operating mode, for setting a biunique correspondence between aphysical position of the actuator and a logic value associated with apredetermined sprocket; and, in a third operating mode, for modifying avalue of the adjustment variable by a displacement of the gearshiftcorresponding to a desired alignment of the transmission element. 45.The bicycle gearshift system of claim 44, further comprising a secondinput device for inputting information on a desired alignment of thetransmission element on the predetermined sprocket.
 46. The bicyclegearshift system of claim 44, wherein the electronic control unitincludes a counter and wherein, in the second operating mode, thebiunique correspondence is setable by setting a value of the counter tothe logic value associated with the predetermined sprocket, and whereinin the first operating mode, the value of the counter is modifiable, inresponse to the displacement request signal, by an amount proportionalto the a difference between at least the first and second logic valuesplus the value of the adjustment variable, and the actuator is drivablea distance corresponding to the value of the counter.
 47. The bicyclegearshift system of claim 46, wherein the electronic control unitcomprises memory for storing the value of the counter.
 48. The bicyclegearshift system of claim 46, wherein the electronic control unitcomprises memory for storing at least one differential amount,associated with at least a pair of adjacent sprockets, for determiningthe logic value of a second one of the pair of sprockets in the firstoperating mode by adding the logic value of a first one of the pair ofsprockets to the differential amount and the value of the adjustmentvariable.
 49. The bicycle gearshift system of claim 44, wherein the atleast one actuator comprises a front and rear actuator for actuating afront and rear derailleur respectively of a bicycle.
 50. The bicyclegearshift system of claim 44, further comprising at least one positiontransducer for detecting a physical position of the actuator andtransmitting a position signal to the electronic control unit.
 51. Thebicycle gearshift system of claim 44, further comprising a power boardfor supplying power to at least the actuator and the electronic controlunit.
 52. The bicycle gearshift system of claim 44, further comprising adisplay unit which is integral with the control unit and the inputdevice.